Neutralisation is the chemical reaction between an acid and a base, which forms water and a salt. The general equation for a neutralisation reaction is:
Acid + base → salt + water
Another way this equation can be written is with the ions:
H+ + OH– → H2O
We use the word base instead of alkali because an alkali is a base that dissolves in water.
Insoluble bases, such as calcium hydroxide, cannot dissolve in water. This means that it can’t form an alkali. However, if you react it with an acid, it will still form salt + water.
Soluble bases, such as sodium hydroxide, can dissolve in water to form an alkali solution. The chemical equation for this reaction is:
Acid + alkali → salt + water
Let’s look at an example:
In this example, hydrochloric acid (HCl) is reacting with sodium hydroxide (NaOH) to form Sodium chloride (NaCl) and water (H2O).
In this case, we have:
To get the name of the salt produced, you use the first part of the alkali (reactant) as the first word. This is ‘sodium’. The second part of the salt depends on the acid used in the reaction. As we used hydrochloric acid, the second part of the name will be ‘chloride’, which will form sodium chloride. This makes the equation:
Hydrochloric acid + Sodium hydroxide → Sodium chloride + Water
The symbol equation for this reaction is:
HCl + NaOH → NaCl + H2O